1. Field of the Invention
The invention relates to a method and an apparatus for separating a disperse mixture of non-miscible liquids, especially to a method and an apparatus for separating a disperse mixture of two non-miscible liquids and in particular of petroleum or gasoline or Diesel fuel and water.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
For separating a disperse mixture of non-miscible liquids, for example of water and petroleum, usually separators are used. Such separators may consist of a tank or container to which the mixture to be separated is periodically or continuously supplied. Typically, partitions are mounted within the separators to create liquid flows for separating solid impurities, for instance sand and chips. The settling and separating of the liquids occurs by means of gravity, thereby forming water and petroleum layers from which liquid is drained by means of outlet branch pipes.
However, water and petroleum mixtures usually consist of water drops dispersed in petroleum or of petroleum drops dispersed in water, i.e. elements of direct and reverse emulsions which are of a high stability. The sizes of the emulsion drops may vary in a wide range, from several micrometers to several millimeters. Consequently, a complete separation of a disperse mixture by gravity requires a substantial amount of time.
Document GB 2.089.670 discloses a method for separating an emulsion of water and petroleum. According to this method, an upper petroleum layer and a lower water layer is created inside a separator. The disperse mixture to be separated is supplied in vertical direction directly into the top petroleum layer. As the water-petroleum mixture passes through the trapping petroleum layer a substantial amount of petroleum from the mixture is kept in the petroleum layer. The mixture passed through the petroleum layer is subsequently fed into the low water layer. The separator further comprises sections furnished with traps to capture petroleum from the mixture. After the separation of the mixture, petroleum and water are drained from the upper petroleum layer and from the low layer, respectively.
However, microscopic studies have shown that passing the mixture through a petroleum layer results in decreasing of the amount of large petroleum drops in purified water whereby, unfortunately, at the same time the amount of fine petroleum drops in water increases. Thus the separation is not satisfactory from an environmental point of view.